1. Field of the Invention
The present invention relates to an ultrasonic diagnostic apparatus capable of acquiring a three-dimensional image, and more particularly to an ultrasonic diagnostic apparatus for extracting a three-dimensional image of a region of interest.
2. Description of the Related Art
An image diagnostic apparatus such as an X-ray diagnostic apparatus, an X-ray CT apparatus, an MRI apparatus, or an ultrasonic diagnostic apparatus is used as an apparatus for taking an image of an internal portion of an object to be examined. Of the image diagnostic apparatuses described above, the ultrasonic diagnostic apparatus has a small size and is noninvasive. In addition, there is no X-ray exposure to the object to be examined. Therefore, the ultrasonic diagnostic apparatus is used for, for example, the diagnosis of the development of an unborn baby.
As shown in a perspective view of FIG. 1A, an ultrasonic probe provided to the ultrasonic diagnostic apparatus includes ultrasonic transducers 21 which are one-dimensionally arranged in a scanning direction (X-direction). Ultrasonic transmission and reception is performed within an X-Z plane by electronic delay control to acquire a tomographic image (two-dimensional image) of the object to be examined. Here, the ultrasonic probe including the one-dimensionally arranged ultrasonic transducers is referred to as a “one-dimensional ultrasonic probe” for the sake of convenience.
In recent years, an ultrasonic diagnostic apparatus capable of performing not only the taking of a two-dimensional tomographic image but also the taking and displaying of a three-dimensional image has been put to practical use and is using in the clinical field. In the ultrasonic diagnostic apparatus, the one-dimensional ultrasonic probe including an oscillation mechanism is mechanically moved to acquire a plurality of tomographic images along a direction (oscillation direction) orthogonal to the scanning direction. A three-dimensional image is generated based on the acquired tomographic images. For example, in the ultrasonic diagnostic apparatus, the one-dimensionally arranged ultrasonic transducers 21 are mechanically oscillated in the direction (Y-direction) orthogonal to the scanning direction (X-direction) to acquire a plurality of tomographic images along the oscillation direction (Y-direction). A three-dimensional image is generated based on the acquired tomographic images. Hereinafter, a plane along the direction in which the ultrasonic transducers 21 are arranged is referred to as a “scanning plane”. The scanning plane is a plane parallel to the scanning direction (X-direction).
As shown in FIG. 1B, development is being made on an ultrasonic probe in which ultrasonic transducers are two-dimensionally arranged to scan a three-dimensional image taking region with an ultrasonic wave, thereby obtaining a three-dimensional image. Here, the ultrasonic probe in which the ultrasonic transducers are two-dimensionally arranged is referred to as a “two-dimensional ultrasonic probe” for the sake of convenience.
In the ultrasonic diagnostic apparatus, ultrasonic transmission and reception is performed on a diagnostic region by using the ultrasonic probe capable of acquiring the three-dimensional image as described above to acquire a three-dimensional image of the diagnostic region. For example, when a three-dimensional image of a head of an unborn baby is to be acquired, a region of interest (ROI) which includes the head of the unborn baby is set in order to display an image of the entire head of the unborn baby. The three-dimensional image in the set region of interest (ROI) is displayed on the ultrasonic diagnostic apparatus.
Up to now, the region of interest (ROI) is set by an operator. For example, before the three-dimensional image is acquired by the ultrasonic diagnostic apparatus, the operator has determined setting conditions (parameters) such as an angle range for oscillating the ultrasonic transducers, an oscillation rate, and a size of the region of interest (ROI), and inputted the setting conditions (parameters) to the ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus has extracted image data included in the region of interest (ROI) based on the inputted setting conditions (for example, JP 2003-275204 A).
However, because the operator has determined the setting conditions (parameters) as to the region of interest (ROI), there have been the following problems. When the angle for oscillating the ultrasonic transducers is insufficient in some setting contents, an image of an entire desirable diagnostic region could not be acquired. When the oscillation rate is too high, an image acquired has become rougher, so that a preferable image has not been obtained. When a width of the region of interest (ROI) is too large, unnecessary data has been acquired to leave an unnecessary image of a region located before the desirable diagnostic region, with the result that the image of the entire diagnostic region has not displayed. For example, when a three-dimensional image of an unborn baby is to be acquired, the three-dimensional image of the entire face of the unborn baby could not be obtained, or an unnecessary image of a region located before the face of the unborn baby is left, so that the image of the entire face has not been displayed.
As described above, it is difficult for even a skilled operator to extract the three-dimensional image of the region of interest (ROI) by the ultrasonic diagnostic apparatus and display the extracted three-dimensional image thereon. When the image of the entire desirable diagnostic region cannot be preferably displayed, until it is preferably displayed, it is necessary to input the setting conditions including the oscillation angle range to the ultrasonic diagnostic apparatus many times by the operator to set the region of interest (ROI), thereby performing the image taking many times. Therefore, there has been a problem in that a time required for examination performed by the ultrasonic diagnostic apparatus becomes longer.